A) Throughout history and today, population growth tends to be most rapid in countries with lower levels of economic development. Specifically this tends two be "stage two" countries. This is for several reasons. First, a characteristic of a "stage two" country is it's heightening crude death rate (cdr). Higher levels of cdr are typically in response from medical advances in more developed countries (mdc) that are then sent to lesser-developed countries (ldc) in the form of foreign aid. These advances in medical technology in turn raise life expectancy and increase the cdr. The reason that these ldc have heightened natural increase rates (nir) over mdc lies in their cultures. In the old days (stage one) many children did not even live till the age of ten, infant mortality rate (imr) were very inflamed and large families were required to take care of the agricultural labor that needed to be done.
Crude death rate by country
World infant mortality rates in 2008. source data
Infant mortality rate world mapToday mdc bring technology advances in farming equipment, which lessens the necessity for manual labor in the fields. Additionally medical advances make sure more people live through their childhood and the conclusion is a rapidly increasing population. Ultimately the rapid population growth is due to the society which has not yet realized or let go of old habits of many children in order to provide the family in its generations to come.